The biomechanics and function of the mid-foot of the feet are critical to normal walking and as well as running gait and biomechanics. The support of the mid-foot of the foot is maintained by a number of factors, such as the shape of the bones, the ligaments, the muscles as well as the plantar fascia. One of the major muscles in the functional support of the arch of the feet are the posterior tibial muscle. This is a powerful muscle that is in the lower leg. The tendon of this muscle passes around the inside of the ankle joint and inserts underneath the bones that comprise the mid-part of the arch of the feet, so this particular muscle is really important for supporting the arch. In some individuals, the posterior tibial muscle appears to lose it capacity to support the feet, causing a disorder known as Posterior Tibial Tendon Dysfunction or alternatively adult acquired flat foot.
This problem typically commences with a moderate discomfort in the arch or inside of the ankle joint and the arch of the feet gradually flattens and the ankle joint rolls inwards. This is all due to the muscle being unable to do its job correctly. If treatment is not started, then the pain and disability progresses. In its later stages it is usually very debilitating and painful. It eventually has a significant impact on total well being and also the ability to walk. It is very tiring because so much energy is required to walk with posterior tibial tendon dysfunction.
Because the long term consequences of this problem can be so debilitating, it's important that it's caught as early as possible and treatment started. The lengthier the delay the harder it is to deal with. In the early stages, the only satisfactory treatment usually are quite firm or rigid foot supports. They need to be rigid as the forces which are flattening the feet are so high that they must be countered. A less firm orthoses will do nothing. A high top trekking or basketball like shoe or sneaker can also be very helpful at stabilising the rearfoot. If this is not satisfactory then more complicated ankle supports will be the next step. If this does not work or the therapy is started far too late, then surgical intervention is usually the only good enough intervention at this stage.